Electronic Journal of Ichthyology April, 2008 1: 31-42 SPECIES RICHNESS, DISTRIBUTION PATTERN AND HABITAT USE OF FISHES IN THE TRANS-HIMALAYAS, INDIA Sivakumar, K. Wildlife Institute of India, P.O. Box 18, Chandrabani, Dehradun 248 001, India [email protected] Abstract The cold desert of Ladakh is a catchment of the Indus river, which contains three major sub- basins: the Indus, Shyok and Zanskar of the higher Himalayas. A survey on lotic water fishes was conducted between April and September 2001 and covered a wide altitude ranging from 2750 m to 5386 m above mean sea level. In total, 41 streams and six rivers were sampled. A total of 32 species of fishes were recorded in the streams and rivers of Ladakh landscape: of which, five were exotic species primarily confined to some sites in the Indus subcatchment. Species richness in the Indus subcatchment was higher (29 species) than other two catch- ments. The Zanskar (10 species) had the fewest species. The current distribution pattern of fish in the Ladakh indicates that this landscape is a transient zone between the palearctic and oriental realms. Fishes in the Trans-himalayas highly used the streams which have more algal growth on the substratum. Snowtrout Diptychus maculates, which occur in abundant in the Ladakh waters would be useful for fisheries. Keywords: fish, snowtrout, Ladakh, Trans-Himalayas, stream fishes Introduction confined to few localities that too focus on The study of fish and fisheries has had a commercial fishes. long and distinguished history in India (Hora Habitat changes in Himalayan waters have 1951), but relatively little attention has been been reviewed (Shrestha 1990) and have paid to fish conservation here. Large number had a major impact on the distribution and of freshwater fishes are threatened due to the abundance of native fishes in mountain fragile nature of freshwater habitats and the streams. The migration routes of important pressure, which they are under in all parts of native fishes such as mahseers (Tor putitora the world from human activities (Le Cren and Tor tor), snow trout (Schizothorax spp), 1964; Maitland 1993; Primack 1998). In In- and Rheophilic species (Psilorhynchus dia, there are an estimated 670 species of pseudochensis, Balitora brucei etc) have freshwater fishes and 227 of these are been impeded because of reservoirs across threatened (Anon 1997). The high percent- rivers. In India, extensive surveys and re- age (35%) of endemic species being threat- search on fresh water fishes have been car- ened is perhaps due to their localised distri- ried out in Kerala, Tamilnadu, Maharashtra bution with other man-induced threats (Pri- and the North Eastern states (Buceros mack 1998). Threats to Indian freshwater 2000), however, no information exists on fishes include habitat destruction, fragmen- the status, distribution pattern and ecology tation, poisoning, pollution, pesticides, de- of fishes in Ladakh. Despite the highly inter- structive fishing unsustainable harvest, poor esting ecological and geographical features scientific practices in fishing and an ever- of the Kashmir Valley and Ladakh (Nath growing demand. In India, freshwater fishes 1994), its fauna have been very inadequately are a poorly studied group, and most of the explored (Hora 1951). In this connection information available is from a few studies an inventory on fishes in 31 Sivakumar, 2008 Fishes of Ladakh Ladakh was thought to be carried out to un- tain chain (79o27’16” to 79o26’01” E and derstand the distribution pattern of fishes 34o35’37” to 35o24’33” N, Figure 1). Trans- and their habitat so that a workable conser- Himalayas is a fragile biome, characterised vation action plan could be prepared. In this by extremes of both climatic and biotic fac- paper the spatial distribution pattern and tors. Very low productivity and a high de- habitat use of Ladakh fishes are discussed. gree of resource seasonality and unpredict- ability give rise to a unique diversity of life Materials and methods that is persistently prone to any kind of dis- Study area turbance. Flora and fauna of this cold desert This study was conducted in three major are adapted themselves to extreme condi- subcatchments of Ladakh: Indus, Shyok and tions and have low population abundance Sanskar. Ladakh represents the Trans- (Anon 2001). Himalayas sector of the Himalayan moun- Figure 1. Study area showing the sampling sites in Ladakh. 32 Sivakumar, 2008 Fishes of Ladakh The river valleys are characterised by riv- subcatchment and hence, equal percentage erbed vegetation communities mostly domi- of streams were sampled in the other two nated by Hippophae sp., Myricaria sp., and subcatchments. Of the 41 streams, 17 were Caragana sp. In the recent past, large scale of the Indus subcatchment, 13 of Zanskar plantations of dwarf willow Salix and 11 of Shyok subcatchment. Three sites daphnoides have been raised along the in 100 m intervals, which starts from the stretch of river valleys. The area receives mouth of the stream were sampled in each less than 100-mm annual rainfall with little stream. Different kinds of nets such as cast snow and is recognised as cold desert. Most net, gill net, mosquito net and lines were rivers, streams and lakes of the Ladakh are used for sampling to maximise the catch and of glacial origin and are frozen from No- cover as much species as possible. Each vember to March. Ladakh has several major sampling point was located using a GPS. river systems including the shyok and Nubra Species and number of individuals of each rivers along the Karakoram range to the species of fish were noted. north; the Indus river system passing from Both omnivorous and herbivorous fishes east to west in the entire central Ladakh; and were caught using lines with atta (wheat three smaller river systems of the Zanskar, paste) as bait and carnivorous fishes were Suru and Dras with a large number of tribu- caught using lines with small fish or meat. In taries in the Zanskar. small streams, mosquito nets were used to The entire Ladakh region is in the catch- catch fish, but in the fast flowing stream ment of the river Indus, however, this large both mosquito nets and 1x1 cm mesh sized catchment can be divided into three smaller fishing nets were used. In fast flowing sub-basins/catchments: Shyok, Indus and streams, fishes were disturbed and forced to Zanskar. Shyok and Nubra rivers and its seek stone shelter and then collected with tributaries (streams) along the Karakoram bare hands. This method was extremely ef- range to the north are collectively called the fective and was used to catch snowtrouts and Shyok catchment. In the Shyok catchment, suckers. streams originate from very steep slopes. Three smaller river systems (Zanskar, Suru Habitat observation and Dras) are collectively called as Zanskar Microhabitats observations were made catchment. Zanskar catchment is a transient from all rivers and streams wherever sam- zone between the Trans-Himalayas and pling took place. For each observation, fish Greater-Himalayas, which is reflected by its were identified to species, their standard own unique vegetation communities that do length and weight was measured using not occur in the other two catchments The vernier calliper and Pasola spring balances, Indus catchment covers the area of down- and the following microhabitat variables stream of the Shyok and the Zanskar catch- were measured: maximum depth of water ments. Indus catchment has heterogenous column, water velocity at the surface and at landscape, which includes undulating terrain the substratum. A pygmy type current meter to flat valley (Anon 2001). was used to measure velocities and depths of water10. Each substratum category (from 1 to Fish sampling 14) was scored in percentage based on a From April to September 2001, 41 modified Wentworth particle scale where: streams and six rivers were sampled and rep- 1= boulders, 2 = boulder with gravel, 3 = resented altitudes ranging from 2750 m to boulder with sand, 4 = cobble, 5 = pebble, 6 5386 m above mean sea level. A total of 17 = pebble with boulder, 7 = pebble with streams found in the Indus were approach- gravel, 8 = pebble with sand, 9 = gravel, 10 able to do sampling which was the 65% of = gravel with pebble, 11 = gravel with sand, the total available perennial streams in this 12 = sand, 13 = silt, and 14 = rocky. 33 Sivakumar, 2008 Fishes of Ladakh Water temperature and turbidity were cies richness across catchments was varied, measured using thermometer and Secchi disc for example, Indus catchment had highest respectively. Nearby vegetation types and number of 29 species, followed by the Shyok channel slopes were also recorded. Discrimi- catchment which had 18 species and 10 spe- nant analysis was used to identify suitable cies were present in Zanskar (Figure 2). Of habitat characters for fish. Non-parametric the 32 species, a total of eight species Dip- tests were used to explore differences in tychus maculatus, Diptychus Schizothoraich- variation in microhabitat characters between thys stoliczkae, Triplophysa microps, Triplo- catchments, and also to identify the differ- phya tenuicauda etc were common and dis- ences in distribution patterns of fishes among tributed in all three catchments (Table 1). catchments. Apart from exotic species, Nemacheilus arafi, Schizothoraichthys labiatus and Data analysis Schizothorax richardsonii were some of the Status of the fishes were assessed based on species exclusively caught in the Indus their abundance. Species occurring at fewer catchments. Indus snowtrout Ptychobarbus than 15 sampling stations (total number of conirostris occurred in Indus and Zanskar, but sampling stations includes 41 streams and 6 not in Shyok. Zanskar did not have any spe- rivers) was called ‘rare’, if it was found in 16 cies exclusive to this catchment. However, to 30 sampling stations was considered ‘not Shyok had three species, which were exclu- common’ and if it occurred in more than 31 sively present there.